If you do not have fertilized eggs, or do not want her to hatch any then you will need to break her. Best way I know is to use a wire crate raised up on bricks or boards so that air can circulate all around her. No bedding/nesting material of any kind, just food and water. Put her in the run or coop in the crate. Leave her there until she changes her mind. It can take a few days or up to a week if she's stubborn about it. If she still fluffs and/or growls, she's still broody. If she goes back to the nest box, she's still broody. They don't eat or drink well while broody, so no reason to put them through it if they aren't going to have babies to take care of. Examples below of a broody breaker set up:
Good job! She is very pretty, by the way. Do you know what kind she is?
